A semiconductor memory device is under developing, which includes three-dimensionally disposed memory cells. For example, a NAND type flash memory device has a structure in which a semiconductor channel body extends through a plurality of word lines stacked on a source layer, and the memory cells are arranged in portions respectively where the channel body extends through the word lines. In such a structure, when the number of word lines stacked is increased in order to advance the integration degree of the memory cells, the channel body becomes longer, and the on-current is reduced which flows therethrough.